闽江学院物理与电子信息工程学院,福建 福州 350108
基于严格的全矢量衍射理论,系统详尽地分析了装校失调对大口径离轴抛物面镜(OAP)光束聚焦特性的影响。研究结果表明,OAP的三维平动及绕轴偏离旋转后衍射焦斑形态没有发生改变,只是焦斑中心位置发生了偏移,利用瑞利判据获得了OAP的三维平动及绕轴偏离旋转公差的量化关系;当OAP发生绕或轴偏离旋转时会引起像散、彗差的出现致使衍射焦斑形态发生变化,产生严重畸变,大幅降低焦斑的峰值光强。并详细探讨了衍射焦斑峰值光强下降10%时容许的最大旋转偏离角与OAP离轴参量、光束参量的变化关系。因此,理解装校失调对光束聚焦特性的影响机制及变化关系,可以为OAP的精密调整提供可靠的理论依据。
激光光学 光束聚焦 全矢量衍射 离轴抛物面镜 失调 激光与光电子学进展
2021, 58(11): 1114006
Author Affiliations
Abstract
Department of Physics & Electronic Information Engineering, Minjiang University, Fuzhou 350108, China
We demonstrate a configuration optimization process of an off-axis parabolic mirror to maximize the focused peak intensity based on a precise knowledge of the tight focusing properties by using a full vector-diffraction theory and obtain an optimum configuration scaling rule, which makes it possible to achieve the maximum peak intensity. In addition, we also carry out an assessment analysis of the offset and off-axis angle tolerances corresponding to a 5% drop of the maximum focused peak intensity and present scaling laws for the tolerances of the offset and off-axis angle. Understanding these scaling laws is important to enhance the focusability of a laser beam by an off-axis parabolic mirror in the optimum configuration, in particular, which is valuable for structural design and selection of an off-axis parabolic mirror in ultrashort and ultraintense laser–matter interaction experiments.
off-axis parabolic mirror laser focusing vector-diffraction theory configuration optimization Chinese Optics Letters
2021, 19(3): 032601
Author Affiliations
Abstract
1 College of Photonic and Electronic Engineering, Fujian Normal University, Fuzhou 350007, China
2 Department of Physics and Electronic Information Engineering, Minjiang University, Fuzhou 350108, China
A tunable dual-band infrared polarization filter is proposed and investigated. Based on the perfect absorption characteristic of the metal-dielectric-metal sandwich structure, the reflection spectrum performs as a filter. The filter consists of three layers. The top layer is a compound metal nano-structure array comprised of rectangular strips. The middle and bottom layers are a dielectric spacer and metal film, respectively. The calculated results show that the filter properties are closely related to the polarization of the incident light. Different dual-band wavelengths are filtered while the incident light has different polarizations, which are parallel or vertical to the x axis. Moreover, it is found that the resonant wavelength strongly depends on the length of the rectangular strip (which causes the resonant effect) and is independent of other strips. Therefore, the filter wavelengths can be tuned freely by adjusting the length of the corresponding rectangular strip. In addition, the calculated results show that all of the intensities at the filter wavelengths are closed to zero, which implies that the filter exhibits good filtering performance.
130.0130 Integrated optics 130.7408 Wavelength filtering devices 130.3990 Micro-optical devices Chinese Optics Letters
2015, 13(3): 031301
中国科学院上海光学精密机械研究所, 上海 201800
利用时谐电磁场和波导理论, 推导出锥形空心金属波导中球横电模和球横磁模各电磁场分量的解析表达式, 对输出孔径是亚波长尺寸的锥形空心金属波导内球横电模和球横磁模的传输特性及与锥形空心金属波导内光透射率有关的时间平均能量密度分布进行了详细的分析。运用数值求解获得的精确本征值, 进一步讨论了光波波长、锥形波导的长度、输出孔径以及锥角对锥形空心金属波导内时间平均能量密度分布的影响。研究结果表明, 时间平均能量密度分布在锥形金属波导内呈现准周期性变化, 且周期与传输模式、锥角及光波波长有关。并且, 在传输径向坐标上会出现一个最大值, 最大值的位置随光波波长、锥角发生强烈的变化。
集成光学 电磁场空间分布 波导理论 传输特性 时间平均能量密度
1 湖南大学计算机与通信学院, 湖南 长沙 410082
2 中国科学院上海光学精密机械研究所高功率激光物理国家实验室, 上海 201800
增益或损耗对光纤的传输特性影响很大。使用Davidenko方法对复折射率光纤的传输特性进行了分析。研究了复折射率纤芯或复折射率包层阶跃光纤,通过比较发现,使用Davidenko方法得到的解与精确解符合得很好。对于芯区为复折射介质的光纤,HE11模与LP01模增益值偏差约为0.6%;对于包层区为复折射率介质的光纤,HE11模与LP01模增益值偏差约为2%。实际研究工作中,为了得到更精确的结果,应该求解全矢量的复本征方程,尤其是包层具有增益或损耗的光纤。
光纤光学 传输特性 Davidenko方法 复折射率光纤
1 湖南大学计算机与通信学院, 湖南 长沙 410082
2 中国科学院上海光学精密机械研究所, 上海 201800
3 中国电子科技集团第二十三研究所, 上海 200437
从波动理论出发,对锥形光纤的纵向传播常数进行泰勒(Taylor)级数展开,经近似得到了锥形光纤功率分布的解。基于此理论,对锥形光纤的功率分布特性进行了讨论,并分析了锥形光纤的长度、锥度和光纤折射率等参数对锥形光纤不同模式功率分布的影响。为了减小功率泄漏,当光从锥形光纤大端入射时,应当减小锥长,减小锥度,增大纤芯包层折射率差; 当光从锥形光纤小端入射时,应当增加锥长,增加锥度,增大纤芯包层折射率差。在长锥长、大锥度情况下,光纤折射率分布的影响相对较小。
光纤光学 高功率光纤激光 锥形光纤 功率分布
华侨大学信息科学与工程学院, 福建 泉州 362021
提出一种由轴棱锥产生的贝塞尔光干涉整形得到具有自成像塔尔博特效应的近似无衍射局域空心光束的新方法。详细分析了两束相干同频率贝塞尔光的相互作用原理及其如何控制局域空心光束的空间尺寸。数值模拟了干涉叠加后光场沿传输距离变化的光强分布及一个完整周期内光强的演变和局域空心光束的形成过程,给出了相干贝塞尔光产生局域空心光束的个数及局域空心光束最大无衍射距离的表达式。
物理光学 相干贝塞尔光 局域空心光束 塔尔博特效应 轴棱锥
Author Affiliations
Abstract
1 Shanghai Institute of Optics and Fine Mechanics, Chinese Academy of Sciences, Shanghai 201800, China
2 China Electronics Technology Group Corporation No.23 Research Institute, Shanghai 200437, China
We propose a kind of photonic crystal fiber with flat-top fundamental mode by introducing a depressed central dip into the core of the conventional index-guiding photonic crystal fiber. The design guidelines and characteristics of the large flattened mode photonic crystal fiber (LFM-PCF) are discussed in detail. By appropriate design, the effective area of the LFM-PCF can be increased by a factor of greater than 2 as compared with conventional index-guiding photonic crystal fiber with the same hole and pitch parameters. The improved effective area, single mode operation and flat-top fundamental mode output make LFM-PCF an ideal candidate to realize high power, high beam quality fiber amplifiers and lasers.
Large flattened mode photonic crystal fiber effective area Collection Of theses on high power laser and plasma physics
2007, 5(1): 227